Gas detection is of importance in a wide range of applications. Petrochemical industries, for example, where safety issues are of particular importance, utilize gas sensors for detection of toxic or flammable gases. Gas sensors are used in process industries to monitor feedstock and measure the abundance of specific gases used or formed during production. In catalytic exhaust cleaning, for instance, gas sensors facilitates simultaneous conversion of NOx to N2 and CO to CO2 and hydrocarbons to H2O and CO2. The use of highly sensitive gas detectors is also widespread in atmospheric science, where they are used to measure and understand the abundance and the pathways of various gas species including greenhouse gases. Reliable gas detection is also beneficial for improved monitoring and analysis of biomarker gases such as nitric oxide, ethane, ammonia etc. during, for example, breath diagnostics.
Qualitative as well as quantitative detection of gases is traditionally performed using conventional laboratory analytical equipment such as optical spectrometers, chromatographs, mass spectrometers as well as semiconductor based gas sensors or electrochemical devices.
The range of applications for gas sensors is constantly increased. In connection with the International Climate Change Panel, ICCP, for example, prognoses for temperature increase and climate change, mainly due to carbon dioxide emission, have intensified efforts to develop techniques for capturing and storage of carbon dioxide. Hence there is an increased need for efficient detection and monitoring of gases such as carbon dioxide, in particular within gas storage media. To this end, there are currently two dominating detection techniques for detecting the presence of carbon dioxide: non-dispersive infrared (NDIR) and chemical sensors. The former relies on the detection of the vibrational modes of carbon dioxide molecules, which are located in the IR range. The latter is based on chemical interactions or reactions that are triggered by the existence of carbon dioxide. These detection techniques have in common that they rely on relatively delicate instrumentation that is relatively large and costly and is difficult to scale down. Hence there is a need to improve gas sensors in general and in particular to provide smaller gas sensors that are efficient in sensing gas.
US 2011/0205543 discloses such a gas sensor comprising a first layer including an array of nanoparticles, and a second layer including a material, which has a porosity of at least 10%. The nanoparticles are provided so as to allow, upon illumination with electromagnetic radiation, long range diffractive coupling of surface plasmon resonances resulting in a surface lattice resonance condition. When the gas sensor is exposed to at least one predetermined gas the surface lattice resonance condition is detectably changed whereby the gas is sensed.
There is, however, a need for improved gas sensors, which are more reliable and robust.